The autoload setting makes the loaded buffer innactive about nvim-possession HOT 1 CLOSED

This is certainly due to some lazy loading that you have for treesitter and lsp, which most likely load later on some specific events that aren't triggered yet when the session is sourced. Notice that in general nvim-possession does nothing except for providing an interface with fzf-lua and some sugar mechanisms to operate with sessions, it doesn't really change or do anything on its own: as such, the problems that you see when loading sessions via this plugin would most likely occur even if you would source the sessions manually by yourself. In turn, this implies that they are due to your specific lazy loading.

See here: autoload essentially sources the session and no more.

One way to fix that i use :e and the buffer refreshes

this is because :e manually re-parses the buffer, forcibly invoking treesitter again.

For reference have a look at my setup: here is my treesitter, here is my fzf-lua and here is nvim-possession. This setup does work :)

from nvim-possession.